<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>class选择器</title>
    <style>
        .box {
            width: 100px;
            height: 100px;
            background-color: red;
            margin: 10px;
        }
        .box2 {
            width: 100px;
            height: 100px;
            background-color: blue;
            margin: 10px;
        }
    </style>
</head>
<body>
    <!-- 页面中可以出现多个相同class的元素 -->
    <div class="box">1</div>
    <div class="box">2</div>
    <div class="box">3</div>
    <div class="box">4</div>
    <div class="box2">6</div>
    <div class="box">5</div>
</body>
</html>